As an example of such a body there may be mentioned, above all, the rotors of large machines, for example turbo-machines or electric machines. Such rotors are usually balanced first of all in the manufacture and thereafter in connection with the erection at the place where the machine is to be used, and then in both cases normally by means of weight balancing, correction balances being placed at appropriate places. This procedure is time-consuming and expensive and does not always lead to a satisfactory result in the case of machines with great susceptibility to unbalance. This is true in particular if the unbalance is due in a minor degree on a real mass unbalance, but more to a deformation of the rotor, in which case weight balancing often does not give good results. In addition, the rotor may change with time, and also the pressure on the rotor may cause a change in balance.
The art also evidences devices to selectively cut away small portions of the rotating body so as to counteract unbalance. See U.S. Pat. No. 3,499,136 and corresponding thereto U.K. Pat. No. 1,178,337.
To be able to satisfy high demands on the balance of a rotary machine it would therefore be desirable to be able to perform an after-balancing of the rotor during operation, and according to the invention a device for this purpose is proposed according to the appending claims.